In recent years, an interfacial phase change memory (iPCM) is developed as one of new semiconductor storage devices. In an iPCM, a crystalline state of a variable resistance element is subjected to a phase change by applying a voltage thereto. By this phase change, the variable resistance element is brought into a low-resistance state or a high-resistance state, and stores data therein on the basis of these two states.
In all resistance random access memories, including the iPCM mentioned above, a magnetic random access memory (MRAM), a phase change memory (PCM) which changes in phase between an amorphous phase and a crystalline phase, and a resistance random access memory (ReRAM), realization of a method and circuit for optimizing a voltage and current necessary for a phase change with respect to a surrounding environmental temperature is desired.